1. Field of the Invention
The present invention relates to optimization of handoffs of a user equipment between packet switched and circuit switched networks as a result of circuit switched network services being requested on the user equipment while resident on a packet switched only network.
2. Description of the Related Art
Traditionally, circuit switched (CS) mobile communication services, such as CS mobile voice communications, have been a foundational service for the cellular voice communication industry. However, current mobile devices or user equipment (UE) are generally capable of providing CS-type services over newer and more efficient packet switched (PS) networks, e.g., Internet/Wimax networks. However, the geographical coverage of PS networks is substantially less than the coverage of the more established CS networks, such as a Global System for Mobile Communications (GSM) networks. One challenge with attempting to provide CS services though a PS network is that not all CS-type services are easily provided through the backbone of the PS network.
Another current type of network is a hybrid packet switched/circuit switched network (PS+CS) or a service enabling network (PS+Cse network), which does not need to support all of the CS network functionalities in one type of network. However, in PS+CS networks, challenges exist with the added complexity of the architecture, protocols, and complex implementation. Therefore, when CS-type services are needed, PS+Cse networks are configured to redirect the UE to the CS network for those particular services. Additionally, the UE does not need to support all of the CS services through the PS network, as the UE has the capability to hand-off from the PS to the CS network for services not easily supported by the PS network backbone.
However, a method or an apparatus is needed to determine when the UE should hand-off from the PS network to the CS network, or a method or apparatus is needed to generate and/or transmit information on how the UE may use the CS services when the current PS network does not provide a particular CS-type service through the PS network. Such method or apparatus is not presently available.
Therefore, there is a need to provide information on when the UE may hand-off to a CS service network when a current PS network does not provide support for a CS-type service requested by the UE. Fulfillment of such need will allow the UE to use PS services via a PS optimized network, while still being able to hand-off to a CS capable network when needed to access communications or services that are better or only provided by the CS service network. Generally, the PS network only needs to inform the UE and/or other network devices how and/or when CS service should/could be used. PS+Cse networks are also able to inform the UE and/or other network components about a UE terminated CS service and provide handoff assistance to the UE to move to/start to use the CS service network as required.
Additionally, fast mobile access to Internet and other PS services plays an important role in the telecommunications industry, as it is the driver for developing various new access technologies like High-Speed Downlink Packet Access (HSDPA), Worldwide Interoperability for Microwave Access (WiMax), 3GPP-LTE (3.9G), IPWs, TDD, and many more. Fast DSL-type service quality (high bandwidth and low delays) is important. Additionally, support of legacy systems to guarantee service continuation when starting deployment of the new technology is also an important consideration. Since it is expected that increasingly more traffic will shift from the CS to the PS domain, while still demanding the services that are essentially exclusively provided by the CS domains, the ability to merge the capabilities of both types of networks remains important.
Examples of services that may take over traffic from the CS domain in more current types of networks, such as PS-type networks, include voice over internet protocol (VoIP) or PS video. Further, an Internet High Speed Packet Access (iHSPA) is one example of such a wireless broadband system. The iHSPA provides the user with a cost advantage because it is both a lean architecture and a PS-only network. The end-user's UE is the same as a “normal” High-Speed Downlink Packet Access (HSDPA)/High-Speed Uplink Packet Access (HSUPA) network, and thus, the user may expect the UE to behave in the same way it always did with previous network communications.
The implementation of the iHSPA is facing the same challenges noted above with respect to the use of PS-type networks providing CS-type services. Due to the PS-only architecture of the iHSPA, the handheld iHSPA UE should be served in the iHSPA when it requests a PS service, and in Wideband Code Division Multiple Access (WCDMA) (or GSM) when it requests a CS or a PS & CS service. However, a challenge with this methodology is that the UE cannot be directed to the correct system before the request is actually made, as the network cannot know which service will be requested before the UE actually makes the formal request. The user manually selecting the appropriate network or system may be in a situation where the network or system is unknown before the formal request is to be sent. However, this scenario is both unlikely and undesirable to the operator of the UE. Therefore, redirection of the UE to the correct network or system should be completed during a call setup phase, if the challenges and problems associated with conventional UE transitions are to be solved.